/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j;

import org.slf4j.MDC;

import java.util.Stack;

/**
 * A log4j's NDC implemented in terms of SLF4J MDC primitives.
 *
 * @since SLF4J 1.6.0
 */

public class NDC {

  public final static String PREFIX = "NDC";

  public static void clear() {
    int depth = getDepth();
    for (int i = 0; i < depth; i++) {
      String key = PREFIX + i;
      MDC.remove(key);
    }
  }

  public static Stack cloneStack() {
    return null;
  }

  public static void inherit(Stack stack) {
  }

  static public String get() {
    return null;
  }

  public static int getDepth() {
    int i = 0;
    while (true) {
      String val = MDC.get(PREFIX + i);
      if (val != null) {
        i++;
      } else {
        break;
      }
    }
    return i;
  }

  public static String pop() {
    int next = getDepth();
    if (next == 0) {
      return "";
    }
    int last = next - 1;
    String key = PREFIX + last;
    String val = MDC.get(key);
    MDC.remove(key);
    return val;
  }

  public static String peek() {
    int next = getDepth();
    if (next == 0) {
      return "";
    }
    int last = next - 1;
    String key = PREFIX + last;
    String val = MDC.get(key);
    return val;
  }

  public static void push(String message) {
    int next = getDepth();
    MDC.put(PREFIX + next, message);
  }

  static public void remove() {
    clear();
  }

  static public void setMaxDepth(int maxDepth) {
  }

}
